Means and method for facsimile recording



Sept 19, 1939 J. v. L.. HOGAN r-:r AL 2,173,113

MEANS AND METHOD FOR FACSIMILE RECORDING Filed Sept. 25, 1936 INVENTOR Patented Sept. 19, 1939 UNITED STATES PATENT OFFICE MEANS AND METHOD FOR FACSlltIlLE RECORDING tion of New York Appueeuen september 25,1936, serial Ne. 102,541I

9Claims.

This invention pertains to facsimile recording devices used as receivers in facsimile transmission systems, either over wire or radio channels, and more particularly to such receivers as embody devices for securing relative motion between a marking stylus and a platen.

'Ihis invention is particularly applicable to such devices which maintain the marking stylus substantially constantly in contact with the rem cording paper surface during the period of recording, suchas in the case of electrolytic recorders. I

This invention includes apparatus for reciprocatingly or intermittently moving a stylus across the portion of a recording paper strip which is in contact with a platen situated beneath the paper, and also includes devices for adjusting the pressure exerted by the stylus upon the paper, while the stylus is in comparatively rapid motion across the surface of the paper, and without interfering with Such motion, in order that the synchronism of the receiving apparatus shall not be disturbed when it becomes necessary to make such adjustment of pressure, thus saving much tiri; and promoting convenience of operation.

One purpose of this invention is to provide mechanism for moving the stylus more rapidly in one direction than in the opposite direction and also-for lifting the stylus from the surface of the paper during the traverse of the stylus in one direction, when it is not marking upon the paper, and for restoring the contact of the stylus with the paper when it is ready to make contact with the surface thereof upon its marking stroke, both of these operations being performed without loss of synchronism and Without substantial alteration of the effective pressure between the stylus and the paper during its repeated marking strokes.

Another object of this invention is to lift the stylus from the platen during the time that it is not situated over the paper, or from the paper during such time as it is desired that no marking shall be made upon the paper, such as for the pur- 45 pose of leaving unmarked margins thereupon, or when it isdesired that synchronizing or other signals be impressed upon the receiving apparatus without any extraneous marks being produced thereby.

Yet another object is to provide a platen in the form of a cylindrical roller, which shall minimize the frictional resistance offered the paper while passing thereover, and at the same time shall afford a linear contact path between the 55 platen and the stylus, during the traverse of the latter. The cylindrical platen likewise distributes the wear thereof over a large surface,` which feature is particularly important in the case of electrolytic recorders, since such wear in this case may be of a chemical nature in addition to 5 the usual mechanical wear, and therefore may often give rise to pitting of the platen surface.

Still another purpose is to provide mechanism for producing a substantially linear velocity of the stylus during its effective marking period, a 10 much greater velocity during at least a portion of its non-marking stroke and a gradual change from one velocity to the other in order to avoid mechanical shock and preserve accuracy of marking.

A further object of this invention is to provide a mechanism for easily and rapidly changing the contact point of the stylus for a new point without the need of elaborate tools or great mechanical skill, so that this operation may readily be performed by a layman in the art, thereby more easily allowing the use and upkeep of a receiver so equipped, in domestic recording service.

In order more completely to describe this invention, we refer to the hereunto appended drawing, where:

Fig. 1 is a plan view partly in section on the lines I-I of Fig, 2, showing a facsimile recorder embodying our invention.

Fig. 2 is a side elevation, partly in cross sec- 30 tion, on the lines 2--2 of Fig. 1.

Fig. 3 is a side elevation, partly in section, on the lines 3 3 of Fig. l.

Fig. 4 is a plan view of a portion of the carriage, partly in cross section on the lines 4-4 35 of Fig. 3.

Fig. 5 is a graphical showing of the timevelocity relations in the operation of the recorder and also showing the distance-velocity relations thereof. 4o

A framework I, serves as a general support for the recorder, and may be constructed of any suitable material of sufcient strength and rigidity, such as aluminum, and the various elements may conveniently be supported by the lateral sections of this framework, as hereinafter described.

Supported upon the framework I0 is driving motor Il, which conveniently may be of the synchronous type, in order to facilitate synchronization when this recorder is used upon alternating current circuits. 'I'he output of this motor is delivered through reducing gears I2 to shaft I3 and upon thisv shaft is mounted a substantially disc-like member Il. Disc Il is provided near its periphery with a stud I5 extending 55 ferent distances between stud I5 and pivot I1 at different parts of the arc described by stud I5, the arm I6 will move at a certain rate of speed in one direction and will move at a much greater rate of speed when returning in the opposite direction. f

In Fig. 1, the arrow I9 represents'an assumed direction of rotation for disc I4 and the full line I representation of arm I6 shows it when it is just commencing to move from left to right in this figure. Under these conditions stud I5 will be at a. comparatively great distance from pivot I1 and accordingly arm I6 will move comparatively slowly. This slow movement of arml I6 is the stroke upon which the recording is done, as later described.

The dotted line representation of arm I6 shows it at the commencement of its return stroke and under these conditions the similar dotted line representation of stud I5 shows that the distance between the stud and the pivot is much less during this return stroke than it was during the marking stroke, thus causing a quick return for arm I6, during the portion of its cycle when it is doing no useful work, and so economizing the time available in a complete cycle.

The outer end of arm IB is provided with a slit 20 and opposite the arc formed by the traverse of the end of arm III, is located a track 2I, so that this track assumes the position of a chord relative to the arc thus formed. During the traverse of the arm, some portion of the slit 20 is always opposite this'track. Track 2I carries thereupon a carriage 22, arranged to slide along the track in grooves 23, 23 running longitudinally of the track. This carriage is provided with suitable wheel-like bearings 24 which engage in the grooves of the track, so that the carriage can move very freely along the length of the track, but has any transverse or rotary motion thereupon reduced to a minimum. The carriage also carries a projecting stud 25 preferably encased in a soft rubber bushing 25. This stud and bushing move longitudinally of arm I3, in slit 20. 'Ihe upper portion of carriage 22 is provided with a projection 21, through which is threaded a screw 28 provided with a suitable knurled head 29. This screw acts to determine the 4space between a clamping member 30 and a fixed back plate 3l, firmly aillxed to the carriage by screw 32. f

In the space between members 30 and 3| is placed a piece of wire or narrow spring 33, bearing at its outer end a marking point or stylus proper 34, which latter may be of any suitable hard material, such as an alloy of platinum or iridium or other chemically resistant material. It can be seen that the stylus member 33, 34 can readily be inserted between members 30 and 3| and that the rotation of screw 28 will then cause clamping member 33 to hold the stylus firmly in place. It is a relatively simple matter` even for one not skilled in the mechanical arts /to loosen screw 28, remove the stylus and substitute a new one therefor, when replacement of the stylus is necessary. We prefer to use a leaf type spring in order to avoid vertical play, and to firmly fasten the actual stylus point to the end thereof. By making member 33 ilt snugly in place on its side edges and against the shoulder of member 30. the correct positioning thereof when making replacements may be assured.

The recording paper 33 may be drawn from a suitable roll and passes over the surface of roller 35. This roller may be formed of any suitable material such as aluminum or other preferably non-reactive conductor such as carbon or the noble metals and is carried in bearings located upon either side of framework III and which serve to afford a good electrical connection between this roller and the framework. as well as allowing the rotation of the roller with the minimum friction. Stylus point 34 is so located that it presses upon the surface of the recording paper, during the movement of the carriage, along a linear path substantially parallel to the axis oi.' the roller.

It will be seen that as the recording ypaper is fed forward by any suitable means, it will be bent in a smooth arc of uniform and slight radius over the surface of roller 35 and that the rotation of this roller will allow the paper to pass thereover with a minimum frictional resistance and also with very little bending of the fibres of the paper, as compared with the case where the paper is fed sharply bent over a fixed platen. Likewise the cylindrical roller promotes the precision of the linear contact provided and makes it virtually impossible for the paper to warp or wrinkle as it passes thereover.

In the operation of electroiytic facsimile recorders it has been found that the maintenance of a proper and uniform pressure between the stylus and the platen is a factor of great importance in determining the successful operation of the recorder. By sliding the stylus element 33 in or out of the space between elements 30 and 3| to a greater or less degree, and then clamping it by screw 23, the eifectivef stiffness of spring member 33 may be varied, thus affording some control of this factor of pressure just referred to. However, such a means of adjustment is not only lacking in precision but also a change of this adjustment necessitates the complete stoppage of the recording operation. Such stoppage is extremely undesirable, not only from the viewpoint of the loss of a portion of the reproduced image but also because it requires the re-synchronization of the receiver, when operation is again started.

Likewise, as previously mentioned, it is often desirable to have element 33 located in the proper position by placing it snugly against the shoulder of element 30 and thus assuring its proper location, for example when replacements are made.

Accordingly we have provided a special device for adjusting this pressure while the recorder is in actual operation, without the need of stopping the same. Y.

Track 2l is carried in framework II) by means of insulated bushings, which act as bearings therefor, thus insulating the track from the framework. An electrical connection is made to any convenient point upon this track, such as one end thereof, as by means of a flexible insulated wire 90. The electrical circuit for supplying marking signals may accordingly have one termlnal connected to the track by means of this insulated wire and the other terminal may be connected to the framework of the recorder. 'I6

the stylus be removed out of contact with the papery during its non-marking stroke. We Yhave found it possible to combine in a single mechanism the means for so removing the stylus from the paper and the means for adjusting the pressure between the stylus and the paper during its marking stroke. A

Itis also often desirable to lift the stylus from the paper not only during its non-marking stroke but also during the marginal portions of its marking stroke. This arrangement provides, inter alia, a positive determination of the blank margins of the paper and also reduces stylus wear. The method of accomplishing this result is by making track 2| capable of rotation in its bearings. This rotation of the track will cause the stylus carried by carriage 22 to be displaced away from the paper surface, when the track is so rotated as to tilt the carriage forward. Likewise it can be seen that if the rotation of the track is capable of adjustment, at one end of the arc of its rotary motion, to a relatively fine degree, the actual pressure exerted by the stylus upon the paper may be varied, without removing the stylus from the paper surface. The movement of the track is brought about through the agency of a main follower arm 40 which rotates about a pivot 4| and which bears at one spot along its length a. stud 42 which may be provided with a suitable bushing 43, rotatable. about stud 42 with the minimum of friction, as by the provision of ball bearings between the stud and the collar. Collar 43 presses against the periphery of disc |4. This periphery does not constitute a true circumferential arc about the center point of the disc, but is so shapedthat one side of the disc has an effective radius greater than the other side, and thesetwo sides are separated by portions of the periphery which are somewhat flattened. Follower arm.4|l is maintained under tension by meanaof spring 44, which ensures the maintenance of the proper pressure between collar 43 vand the periphery of disc |4 at all times. As disc I4 revolves, it can be seen that follower arm 40 will assume two distinct positions according to whether the disc is presenting its maximum radius or its. minimum radius to roller 43 carried by the arm. The flattened portions of the periphery of discl |4 will allow arm .40 to pass from one position to the other.

There is provided an auxiliary follower arm 45 which is clamped about the rounded end 46 of track 2| by means of a suitable opening in the follower arm` and the provision of a clamping screw 41. Any movement imparted to the free end of auxiliary follower 45 'will then result in rotation of the track 2|. The .free extremity of auxiliary follower 45 is provided with a projecting pin 40 which engages a groove 49 provided in the surface of another pivoted arm 50. Arm 50 is moved by main follower arm 40, when the latter oscillates about its pivot 4|. This arm 50 serves to operate paper feeding mechanism which is shown in part in Fig. 2 but which is not described in detail, as this particular form is not essential to the present invention.

Arm 5|| may then be considered for the purposes of the present description, merely as an extension of main follower arm 40 and the back and forward movement of arm 50 will result in the raising and lowering of pin 48, thus causing track 2| to rotate and thus to vary'the position of the stylus with regard to the paper. Auxiliary follower 45 is insulated from framework III, by covering pin 4I with an insulating collar 52 and since this auxiliary arm is supported from the track 2|, it will be insulated at its other end for the same reason that the track is so insulated.

Auxiliary follower 45 is provided with another laterally extending pin 53 covered with an insulating collar 54. A tension spring 55 is fastened around the collar at one end and to a suitable point of the framework 56 at the other end. This spring tends to keep pin 4l in contact with the surface of groove 49. and tends to rotate track 2| in such a direction as to keep the stylus in contact with the paper, when follower arm 45 is not forcibly directed in the opposite direction. The i maximum extent to which spring 55 may rotate the track will be determined by the contact of 4collar 54 with a shaft 51 which functions as a stop. Shaft 51 is formed as a prolongation of the threaded portion 5l of a screw provided with a knurled head 59 conveniently located exteriorly to framework ill and provided with a coil spring 60 located between the. knurled head and the framework. The rotation of the knurled head 5S will then cause the slight rotation of track 2| which `may be needed to adjust the pressure of the stylus upon the paper and also will determine that after the stylus has been completely removed from the paper surface before or at the beginning of the non-marking stroke, it will return again into contact with the paper with sub` stantially the same amount of pressure exerted thereupon.

We have found this uniform pressure of the greatest importance in securing uniformity of density in the successive lines making up a reproduced image, as well as in causing the stylus to glide smoothly over the paper surface without picking up fibres therefrom.

In Fig. 5, the vertical axis represents the velocities of translation of the stylus carriage and the upper horizontal axis represents the time elapsing. The duration of one complete cycle is shown in this graph, The portions |00, |||II represent the intervals during which the stylus is passing over the two margins of the record strip. During these times the stylus is not marking and preferably is out of contact with the paper. Accordingly the non-linear velocities are then unimportant.

l The substantially-linear portion ||I|, of this graph, represents the time-when the stylus is marking and is secured by, inter alla, offsetting the increase of arm rotational velocity due to the increase of effective lateral motion of the cam stud with a decrease of carriage velocity due toits distance from the arm center of radius i1 being decreased. Both these velocity changing effects `are present when the carriage approaches the centre of its traverse and by suitable choice of the various dimensions involved, according to wellknown mathematical principles, the two effects may be substantially counterbalanced so as to give very nearly uniform velocity during the active portion of the marking stroke, which may the traverse.

occupy approximately fty percent (50%) the total lhe portions iti, of graph repi the two end rtious of the baci; stroke stylus, and portion t3 is the central po The time needed .tor tl plete ctroise is much less than .tor the ing strole, to the lessened eirective distance between the driven portion of the arm an centre ci radius. we may secure a su7 tially imirorm and slow active portion the marking strolre, a uon-uniiorm margin, and a non-uniform rapid retur stroke.

From this graph it can be seen that for the adJ tive portion oi the marking stroke, taking place during about one-:halt the total cyclic time, the velocity ol the stylus need not vary more than a few percent from its average value'. This uniformity is still more evident in the lower graph in Fig. 5, where the lower horizontal axis represents the distance traversed by the stylus during its marking stroke, and the vertical axis continues to represent velocity. From this it may be seen that at all times except when at the margins, the stylus'has almost constant velocity as indicated by the slowly changing curve portion lilo, thus aiding in securing a reproduced image hav-- ing minimum distortion even when the scanning at the transmitter is performed at a uniform. velocity, s inthe case oi a drum type scanner. This lower graph also shows that the stylus velocity is so proportioned that only comparatively small portions oi its working stroke as indicated by the portions it, itil are unavailable for -marking when uniform velocity is med the transmitter. lin such case these unavailable pora 4tions conveniently may be used as margins to the record strip. They may also be used for marking by making the transmitter scanning velocity change according to substantially the same law.

In the upper graph oi 5, it will he noted that the return portion oi a cycle, lilZ, lill, W2, is almost sinusoidal in shape, as it has been found that such a shape curve represents a type of moa tion which gives rise to the least mechanical shock, so that the trame of the apparatus moy be made oi lighter weight than otherwise would be possible, the gradually changing acceleration so provided permits greater marking precision to be obtained. by allowing the use of more rugged and positive stylus carrier and stylus driveelen ments than otherwise.

l't is to be understood that li'ig. 5 is merely ,illustrative of one particular set of design factors,

and the various portions thereof can be modliied by suitable choice of these design factors. Furthermore, the arm drive here shown may be replaced by an internal or external follower, held tightly, as by a springto the contours of a cam of any desired shape,

It is possible not only to secure the substantially I linear velocity of marking stroke for nity percent (50%) of the time, but also to secure and use non-linear velocities during this period, if so desired, provided that the transmitter and recorder are both supplied with cams or other drives giving substantially similar time/velocity graphs. It is to be notedv that we provide a positive drive for the carriage at all times, rather than depending upon spring returns or the like, of uncertain and easily variable velocities.

While we have herein described a recorder of the reciprocating type. yet many of the features described, such as the adjustment of stylus presin addition, the use ci a photo-electric cell or electrouoptical translation o vice :in lieu i the stylus storni will perdait our Jriltion to be a? to a a imile transmitter, by such simple changes as will be obvious to those skilled in the art.

We claim:

l. lu a iacsimile recorder e com, .means ior rotating the cam, a stylus reciprocatingly driven by one portion of the cant, follower resting upon another portion oi? ne cam and oscllated thereby between `two substantially stationary po sitious and means actuated by the follower whereby one position of the follower allows said stylus to rest upon a recording surface and the other position of the followercontrols the amount of space between the stylus and said surface.

2. A facsimile recorder including a stylus, a platen for supporting a recording surface and a cam, means for rotating the cam at a speed synchronously related to signals received by said recorder, a mechanism actuated by the cam and raising the stylus from said surface during a portion of a complete rotation of the cam and allowingl contact between the stylus and said surface during the other portion oi a cani rotation, and a device associated' with said cam and actuating an oscillating arm which determines the reciprocating motion of the stylus across said surface, whereby said periods of contact between said stylus and said surface and the' motion of the stylus across said surface are synchronously determined by said cam.

3. The method of facsimile paper recording by a moving stylus resting against paper passing over a rotary cylindrical platen, which includes the steps or" rotating the platen solely by the friction of the paper passing thereover, moving the stylus at a relatively slow speed along the length of the platen in a substantially linear path, while maintaining contact between the stylus and the paper, removing the stylus from contact with the paper, moving the stylus in the opposite direction along the length of the platen at a relatively high speed and restoring contact between the stylus and higher rate oi speed, independent means for varying the operative pressure oi' the stylus upon the paper, and stationary control means situated remotely from said stylus and acting upon said pressure varying means whereby said variation may be made without impeding the freedom of motion of said stylus, while the latter is in scanning motion.

5. A reciprocating facsimile scanner including a marking element, means for moving said marking element in one direction at a rate of speed substantially linear for the marking portion of said unidirectional movement, and means for positivelgmoving said element in the opposite direction at a. greater rate of speed, and also including means for gra/dually changing from one Arate of speed to another, whereby mechanical amano said motion at a higher rate of speed is substantially sinusoidal over at least a portion of its cycle.

7. A facsimile recorder including driving means, driven means rotating in a circular path. an oscillating arm driven by said rst driven means, a track forming a chord to the arc described by said arm, a carriage driven linearly along said track by said arm, a stylus carried by said carriage, a marking platen for supporting a recording surface, and means for putting said stylus into contact with said surface when moving in one direction, and keeping said stylus out of contact with said surface when moving in the other direction.

8. In a fascimile scanner, the combination of a platen for supporting a recording surface, a

marking electrode, means for moving said elec' trode back and forth across said surface, means for guiding motion oi' said electrode, means for making and breaking contact between said electrode and said surface, means for determining the point oi' contact between said electrode and said surface, and means for determining the path length of said electrode across said surface independently of said point of contact.

'pressure of one oi' said electrodes upon said sheet.

and stationary control means situated remotely from saidl electrodes for controlling said pressure varying means.

JOHN V. L. HOGAN. HORACE G. MIILER. 

